How to configure Chrome (in Ubuntu) to handle ssh://user@hostname links

The easy answer is: you don't. Chrome handles all "weird" protocol URLs to xdg-open. And you configure xdg-open via xdg-mime. You've to create a *.desktop file and reference it via xdg-mime to handle the x-scheme-handler/ssh mime type. And you can point (in your *.desktop file) to a custom shell script to do the actual URL handling: